Measuring devices using capacitive or conductive principles are equipped, as a rule, with an essentially cylindrical probe unit, which is introducible into the container. Known for fill level measurement, on the one hand, are rod-shaped, probe units reaching vertically into the container for continuous determining of fill level, while known for limit level measurement, on the other hand, are probe units introducible into the wall of the container. Both variants have at least one probe electrode. Especially in the case of the embodiment of the probe unit for limit level registration, the probe electrode is surrounded preferably at least in the region of the process connection coaxially by a guard electrode, wherein the guard electrode and the probe electrode are isolated from one another by electrical insulation. Via the capacitance between container wall and the probe electrode and/or between the medium and the probe electrode, the fill level of the medium in the container is determinable.
Methods for capacitive fill level measurement are disclosed, for example, in the Offenlegungsschrifts, German laid-open applications, DE 10157762 A1 and DE 10161069 A1.
Known from the state of the art for contacting electrodes are, on the one hand, cables with wires, wherein the wires are soldered onto contacting elements and the cables terminate in a shared plug. On the other hand, flexible circuit boards are used for different applications. For example, European application EP 1378014 B1 describes a flexible circuit board for contacting piezoelectric elements arranged in a stack. For this, the circuit board includes a plurality of contact plates, which, by bending back and forth, can be adhered between the piezoelectric elements. This contacting method, indeed, saves space; the applying of the contact plates, however, requires some time and dexterity.